1. Field of the Invention
The present invention relates to a method of adjusting the position of an information record reproducing transducer (e.g., a magnetic head) employed for a medium-replacing type information storage system such as a flexible disk system.
In the medium-replacing type information storage system such as the flexible disk system, the distance of the information record reproducing transducer (hereinafter called magnetic head) from the center of a spindle for driving a recording medium must be set at a definite value so that the relative position between the magnetic head and recording tracks of said medium may not be varied even when the medium is replaced. In this regard, adjustment has been conducted in a flexible disk system having only a magnetic head for one side of the recording medium, by measuring optically and directly the gap position of the magnetic head from the center of the spindle. In a flexible disk system whereon a magnetic head for both sides of the recording medium is mounted, on the other hand, it is impossible to measure optically an opposite head gap, and therefore a disk for adjustment wherefrom specific signals for position measurement can be obtained, such as disclosed in the Japanese Official Gazette on Japanese Patent Publication No 7142/1984, for instance, is used therein generally. According to the adjusting method wherein said disk for adjustment is used, the disk for adjustment is set in the flexible disk system, the correctness of a position of the magnetic head is observed on the basis of signals obtained from the magnetichead, and the position of the magnetic head is adjusted in accordance with the result of the observation.
This method enables the measurement of an amount of deviation (hereinafter called off-track amount) from an ideal position of a double-side head in some specific track for adjustment, and therefore it is possible to conduct adjustment so that the off-track amount of each magnetic head be minimum. However, this method can not always lessen the maximum value of the off-track amount in all the recording tracks of a disk, since the adjustment is conducted only with the specific track taken in view. For instance, in a magnetic head positioning mechanism disclosed in U.S. Pat. No. 4,161,004, which comprises a step motor, a belt wound once on a pulley of the step motor and a carriage fitted with said belt and supporting a magnetic head, a positioning error of the magnetic head results from the precision of a feed angle of the step motor serving as a driving source, errors in the radius dimension and eccentricity of the pulley fitted to the shaft of the step motor, an error in the thickness of the belt wound on the pulley, hysteresis generated in positioning the step motor as the result of the direction of movement, etc., and this has been a large hindrance to making high the density of tracks.
Various efforts have been made to reduce the respective factors of the above-stated errors, and in this relation, there have been proposed methods intended to improve a machining dimensional precision of each component, to reduce the hysteresis and improve the positioning precision as disclosed in the Japanese Official Gazettes on Japanese Patent Laid-Open No. 152723/1982 and Japanese Patent Laid-Open No. 152724/1982, and to remove errors in the eccentricity of the pulley and the thickness of the belt, from a structural point of view, as shown in the Official Gazette on Japanese Patent Publication No. 38783/1985. None of these methods, however, has succeeded in lessening the maximum error of all the recording tracks.
Such a system as shown in the foregoing Official Gazette on Japanese Patent Publication No. 7142/1984, in which specific signals for position measurement are written in a plurality of disks for all the recording tracks, has been marketed. In this system, however, it takes too much time and increases the number of recording tracks unreasonably to measure and adjust in advance errors occurring in writing the signals among a plurality of disks as well as an error in each recording track revealed when said signals are reproduced from all the tracks.
In the above-described prior arts, no consideration is given to the appropriate adjustment of the errors in all the recording tracks as well as to the quick measurement of said errors and the easy adjustment of the position of a magnetic head, and this has been a problem which hinders making high the density of tracks of the flexible disk system.